Salifert Boron is an essential element and this Salifert Additive contains blended, boron containing salts. This additive does not contain the toxic boric acid compound but is, within 24 hours, gradually converted to the desired boric acid. This method has several advantages since, when added to the aquarium a locally high concentration will be present until evenly mixed throughout the whole aquarium. If the additive was boric acid then some slight but temporary toxic effect could take place, a danger prevented with the Salifert additive. Available in 250 ml size.